Well, according to Paul (Romans 14:17) the kingdom of God was the sending of righteousness, peace and joy through the Holy Spirit. If we take Paul's words to be accurate then he was likely referring to the day of Pentecost when the kingdom of God was established through the sending of the Spirit to dwell with man. Per the words of Jesus, the kingdom of God is within us (Lk. 17:21). We can become Gods' building, a temple of the Holy Spirit. The Jews were imagining instead a new physical kingdom that would drive out the Romans and allow them to live in peace. Jesus corrected them that the kingdom of God is within a person, not a physical kingdom.

Jesus came in the figure of God the father. He said he would not leave us orphanos (Jn 14:18--comfortless in King James but is originally written as orphanos or orphans.) One can then view the Holy Spirit being a representation of the other parent now dwelling with us, no longer leaving us as orphans and making us citizens of a more perfect kingdom...the kingdom of God.

Jesus more or less solidified this outlook when he spoke to the Pharisees in Matthew 28 --But if I cast out devils by the Spirit of God, then the kingdom of God is come unto you.

There is much more that can be said about the Kingdom of God, since it is multi-faceted, and your approach may be yet another of those facets.